Concrete wall construction



July 4, 1933. F-A. REINHARD 1,917,062

CONCRETE WALL CONSTRUC'I'IOM Filed Sept. 10, 195o Y I?? 11671 fr Iig.www/M l Patented July 4, 1933 UNITED STATES PATENT OFFICE- FRANK A.BENHARD, F NORTON, MASSACHUSETTS, ASSIGNOR TO LAWRIE L. WITTER,

0F BOSTON, MASSACHUSETTS Y.

CONCRETE WALL CONSTRUCTION Application filed September 10, 1930. SerialNo. 480,932.

This invention relates to concrete wall construction and moreparticularly to a means and method for preparing a concrete wall forreceiving and retaining a plaster or like finishing coat thereover. Itis well known that walls of buildings constructed of concrete areplaster-receiving surface in the moulding` operation but these devices'have not been successful for various reasons, particularly since a firmbond has not been secured and the devices have been inoperative,unreliable or too expensive. The primary object of my invention is toproduce a simple, inexpensive and reliable method of providing theseconcrete walls with undercut surfaces by which a strong and secure bondisformed with the plaster coat placed thereon, the method embodying theuse of a simple and inexpensive moulding mat which may be repeatedlyused in successive moulding operations.

My invention particularly embodies the use lof a resilientlycompressible moulding mat of rubber o r like material .having undercutcement-recelving surfaces shapedy to form undercut plaster-receiving andretaining surfaces on the concrete wall, it being understood y that myimproved moulding mat is to be used as a liner for the moulding-formwall. The matis constructed to form undercut projections extendingoutwardly from the wall, and 1s so resilient and compressible that afterthe concrete has set the mat can be readily stripped therefrom withoutinjury. The mat is an extremely simple and cheap article of manufacture,comprising simply a plain mat with undercut'holes therethrough.Furthermore, the use ofthe mat for the purpose stated is also extremelycheap since there is little wear on the mats and they canbe usedrepeatedly for an indefinite period. The production of such aninexpensive method and moulding mat for the purpose stated comprises afurtherobje'ct of my invention herein.

In the accompanying drawing, I have illustrated certain specificembodiments of my invention but it will be understood that the inventioncan be otherwise embodied and that the drawing is not to be construed asdefining or limiting the scope of the invention, the claims appendedhereto being relied upon for that purpose. l'

Referring to the figures of the drawing:

Fig. lis a. fragmentary view showing the use of my invention inconstructing a vertical poured wall.

, Fig. 2 illustrates the same after the forms have been substantiallyremoved and the wal partly completed.

Fig. 3 is a fragmentary perspective view I of one form of my improvedmoulding mat.

Fig. 4 is a sectional view through a floor, the bottom or ceiling sideof which is finished in accordance with my invention.

As has been heretofore stated, the exposed surfaces of concrete wallsare usually finished by a coating of Irelatively inerplastic material,such as plaster, and the purpose of my invention is to provide a meansand method of performing this operation with greater economy, facilityand efficiency. `My invention particularly involves the use of areslliently flexible and compressible mat, of rubber or like material,which is so shaped and used as 'to provide a plurality of undercutbonding surfaces on the concrete walls which are' tobe plastered. Themat is of such substantial and solid 4construction as to withstand thepressure exerted' thereagainst' by `the soft concrete and is soresiliently flexible and compressible as to be readily removed from thehardened Walls and particularly from the undercut surfaces formedthereon.

Thel preferred form of my improved moulding device yis shown at 10 andcom- 'lprises a plain rubber mat having a plurality of frusto-conicalholes 12 therein land preferably extending therethrough. The use of themat in forming a vertical 'concrete wall4 is illustrated in Fig. 1. Thepurpose of the mat is to so shape the Wall surfaces that they Willlreceive and securely hold the plaster finish coating. The Wall forms 14are therefore lined With ortions of my improved mat 10 as shown in 4ig.1, the larger ends of the holes 12 being adjacent to the forms 14 andthe mats being lightly secured to the forms by any convenient means.When the concrete 16 is poured, it runs into and fills the holes 12 asWill be understood.

After the Wall has set or hardened, the forms 14 are removed and themats 1() may be readily stripped therefrom as shown in Fig. 2. When thusstripped, the Wall surface 18 is left with a plurality of frusti-conicalprojections 20 providing undercut plaster holding surfaces at theiredges 22. When the finishing coat 24 of plaster is applied to this Wall,it so moulds over and about these projections and surfaces as to form afirm holding bond, clearly illustrated in Fig. 2. The mat 10 is of solidconstruction and of a thickness only sufiicient to provide projections20 of the necessary length to retain the plaster coating 24, and in viewof the relatively close arrangement of the holes 12 and projections 20,the mat is ordinarily relatively thin as illustrated. It should befurthermore noted that the providing of holes, and especially roundholes, in the mat renders it more substantial and less liable to iningrelatively long openings or recesses there- 1n. Thefmat, therefore,provides a firm and substantial lining for the forms 14 and may beapplied thereto and used with a minimum expenditure of time and cost.When the Wall is hardened, the sides Will be found as true as the innersurface of the forms due to the construction of the mat lining as abovedescribed. It Will also be understood that the hnmg may be easily andreadily stripped from the hardened Wall Without injury to elther the mator Wall, since the mat does not adhere to the Wall and the only'clingingportions are the relatively small undercut surfaces of the holes 12.

While I have above described a vertical Wall, it will be obvious that myinvention is by no means limited thereto. For example, in Fig. 4 isillustrated a horizontal Wall 30 providing a floor surface 32 above anda ceiling beneath. In constructing this Wall, the top surface of thehorizontal floor form is lined with my improved mat and the concrete 30poured thereonto. When the Wall is set, the form and mat are removed inthe manner above described. The plaster 34 is then applied and forms abond with the projections 36 as will be understood.

I am aware that corrugated metal is being used to provide a lbondbetween the concrete Wall surface and the plaster coating, the metalbeing moulded into the concrete Wall surface and the plaster thereafterbeing applied to the outer surface of the metal. This method has variousand serious objections which are entirely eliminated by my improvedprocess. The metal encloses the concrete so that it cannot properly andthoroughly dry and the metal thus retains a considerable amount ofmoisture at its inner surface. This moisture not only prevents properdrying and hardening of the Wall but also causes the metal to rust andthereby eventually become useless as a bonding medium. On the otherhand, my improved process completely exposes the concrete wall andpermits it to freely drain and dry to any degree desired l fore theplaster is applied. It is believed that the many other advantagesresulting from the use of my invention AWill be clear and obviousWithout further description herein.

I claim:

1. In a mould for forming a cementitious Wall with a bonding surfaceincluding underl `.cut projections for retaining plaster or the jurythan would be the case With a mat havlike, a fiat supporting form, alining thereon comprising a fiat mat having cement receiving holestherethrough and the Walls of Which are shaped to form said undercutprojections, the mat being so resiliently iexible that lit may bestripped from the set Wall Without injury.

2. In a mould for forming a cementitious Wall with a bonding surfaceincluding frustoconical projections for retaining plaster or the like, aflat supporting form, a lining thereon comprising a flat mat havingfrusto-conical cement receiving holes therein with Walls shaped to formsaid projections, the mat be- Ving so resiliently flexible that it maybe stripped from the set Wall without injury.

3. A mould lining comprising a resiliently lieXible mat of rubberor likeresiliently flexible material having a plurality of round and undercutholes therethrough.

4. A mould lining comprising a resiliently fiexible mat of rubber orlike resiliently flexiv ble material having a'plurality of frustoconicalholes therein.

In testimony whereof I aiiix my signature.

FRA A. RE

